Enviros are planning to lobby against a proposal in President Clinton’s new budget plan that would give the U.S. Forest Service wide authority to sell public lands. White House officials say the language is intended to help the government swap public tracts for more desirable private ones, but enviros say that if a conservative administration came to power, the proposed change could give it the authority to sell off vast tracts of land. The legislation, which would include some limits to avoid land-sale abuses, might appeal to many Western members of Congress who are pushing for more local control of public land.